Ajustement osmotique et maintien de l'activité photosynthétique chez le blé dur (Tricum durum, Desf.), en conditions de déficit hydrique

Abstract

The multiple approaches proposed for an efficient selection are based on mecilanisms, which are linked to plant behavior. Thus, in order to increase the efficiency selection for programs improvement. This study, aims/tent to analyse the effect of osmotic adjustment in condition of water stress besides the maintenance of a sufficient photosynthetic activity on some variety of hard wheat cultivated in Algeria. The characters, which explain the osmoregulation phenomena, and which are linked to water status, photosynthetic activity, and osmolyt accumulation are analysed. The recovering capacity of tested cultivars is estimated after measure of the same parameters before a period of recovering. The obtained results revealed that: The aptitude to realize an active osmoregulation is linked to genotype and not necessarily linked to superior aptitude to maintain high relative water content nor more negative osmotic potential. The osmolyt that characterize the osmotic adjustment on one hand and a best tolerance to water stress in the other hand, are sugar “ glucose" in particular. In our case the proline is not an important osmoticum. A good capacity of osmotic adjustment is observed at varieties such as: T.polonicum, Cir, H3, Mtp and W, these varieties represent an important level of photosynthetic assimilation. However, the osmoregulation aptitude is less important for varieties such as: GGR, Vit, B17 and In69. Genotypes such as: T.polonicum, Cir and H3, iend to have an aptitude to water stress shortage through better use of water and C02 assimilation at “stomata” level. The local genotypes are more efficient under stress. The recovering aptitude of the different cultivars is mainly due to intrinsic characteristics. The different variables are on the same level of the non-stressed plant, and the studies varieties express an important recovering of their photosynthesis activity. As a conclusion, it is clear that the great variability observed for the different varieties and analysed variables and, their relation to drought tolerance, permits to illustrate the interest of osmotic adjustment in maintaining the photosynthesis activity of stressed plants. This suggests, the use of this parameter as a selection criteria to improve tolerance and yield